Madrid, Spain: Struggling Chelsea striker Alvaro Morata's woes continued Friday when he was left off Spain's squad list for international friendlies with World Cup big guns Germany and Argentina, against whom the returning Diego Costa should feature.

Morata began strongly after he arrived at Chelsea in the summer but his form has deserted him and he has not scored since December 26. He started on the bench in Chelsea's midweek defeat at Barcelona.

"He's had a series of physical problems he's not playing much and we decided to bring in another player," said Julen Lopetegui, the Spain manager, insisting Morata "is always in our thinking and his chances of going to the World Cup are intact."

The man Morata replaced at Chelsea, Costa has hit six goals in 13 starts for Atletico Madrid since January and returns to the Spain squad for the first time since June 2017.

While omitting one Chelsea player, Lopetegui has called up another, Marcos Alonso, for the first time. If the 27-year-old wingback makes his debut he will follow his father and grandfather in playing for Spain.

Spain, the 2010 World champions travel to Dusseldorf on March 23 and then host Lionel Messi's Argentina at Atletico Madrid's new Metroplolitano stadium, where Costa will feel doubly at home.